CIGWELD TRANSarc 130i, Руководство по обслуживанию

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TRANSARC 170i
Manual 0-5280 6-17 Troubleshooting
6.13 Main Circuit Description
!
WARNING
Turn off power and disconnect mains supply plug from receptacle before working on the unit. Allow
two minutes for capacitors to discharge after disconnection from mains supply voltage.
A-11868
The mains supply voltage is connected via a double pole switch to the input rectifiers on the main inverter board
through an inbuilt EMC filter on the inverter power board. Overvoltage protection is provided by varistor CY1.
The rectifier output charges the main capacitor bank (C17, C19, C22, C23, C24 and C25) to high voltage through
PFC IGBT’s V8 and PFC diodes V7. Inrush current limiting is provided by an off board resistor R2 which is then
bypassed by relay J1 after a few seconds.
The primary igbt transistors (Q1, and Q2) switch the transformer primary at high frequency and varying duty cycle.
The transformer return wire is taken from the terminal centre of the main DC bus capacitor bank (the voltage at
this point is approximately half the DC bus voltage).
Secondary output voltage from the transformer is rectified by the output diodes (T14, to T18) to DC. This DC is
controlled by the PWM of the primary side igbt transistors, and is filtered by an inductor before connecting to the
welding output terminals.
A thermal overload device (thermal switch) is fixed to the rectifier heatsinks. When an over temperature occurs,
the control circuit inhibits the trigger, gas solenoid, and the welding output. The thermal overload indicator LED
on the front panel is illuminated.
The current transformer CT1 provides a signal to the control circuit to indicate both transformer primary current,
and also detect transformer saturation. The Hall effect current sensor CT2 is powered from reg & - 15VDC
supplies and provides a voltage signal proportional to the output welding current to allow the control circuit to
regulate welding current.